Fallen off the cliff on Yahoo and Bing

Hi folks. I have inherited a site that used to get 20% of its search engine traffic from Yahoo and Bing and 70% from Google. In the past three months Yahoo and Bing traffic has gradually declined until it is now 0% and Google accounts for 95 to 97% of the traffic. The rest of the traffic coming from Russian and other smaller search engines. Come to think of it, used to get fair number of inquiries from Ask as well but they have also disappeared. Any insights on why this could have happened.

Have inquired my predecessors and they are telling me that they never optimized for any other engine but Google so are equally puzzled. Any insight will be appreciated. Not sure if mentioning site is allowed, if not allowed, please edit it out of the message. Site is New 2014 2015 Toyota Hilux Vigo Minor Change Model

Your backlink profile looks very iffy. Lots of links from unrelated pages. Looks like whoever was doing SEO before you was being pretty spammy about it but on a low level - forum/blog commenting, etc. You've got links for pages such as "What is the meaning of f#$k" and stuff.

Bing is a bit more sensitive to links than Google - could be your woes. Alternatively did your impressions in Bing start to drop before your rankings?